Flexiblade is a super aggressive trimmer line designed to take on the toughest jobs. The patented cutting system is so aggressive, it will cut weed stocks up to 3/4" in diameter with ease. Serrated edges will even handle brambles and berry vines. This line will fit into most manual feed trimmer heads, but is not recommended for "bump feed" trimmers. Avoid contact with concrete, rocks and wood. The sharp teeth can damage trees, walls and fences.